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At 5:18 PM -1000 8/8/96, Richard Pyle wrote: >> In "The Mixed Gas Diving Book" by Gilliam, mount, et al... There is a table >> listing the narcotic properies of most gases. Does anyone have the data >> for oxygen??? > >Looking only at lipid solubility (which I believe is what the table you >mentioned is based on), O2 should have about twice the narcotic potency >of N2. However, real-world factors greatly obscure the actual role >played by O2 in causing narcosis. In some cases, (PO2 < ~1.4) it seems to >cause less narcosis than the equivalent N2. In other cases (PO2 > ~1.6) >it seems to be more potent. A good rule of thumb is to assume it is >about equipotent for nrcosis as N2. Rich, my thinking may have been all wrong since I was trying to isolate the narcotic from the convulsive effects of O2 and clinically that may be appropriate. If these numbers are in the ballpark, than narcosis may be merely the physiologic/clinical * prequel" of the convulsions. If a convulsion is the clinical manifestation of massive, electrical discharges in the brain (with *EVERYTHING* going to pot all at once in a manner of speaking) narcosis is the clinical manifestation of smaller alterations in selective areas of the brain (which we already know to be O2 selective in their usage). In this situation the convulsion is an avalanche and the narcosis is the early rolling pebbles. So to elaborate on my last post to you, it may not only be that the narcotic effect of O2 is swamped out by the greater volume of inert gas (N2,He2 or even Neon) but that the O2 narcotic effect may occure close enough to the convulsion indusing levels of electrical activity that narcosis cascades into a convulsion quick enough not to be noticed. What we need is to lock a good neurologist in the same room with Bill Hamilton and let them slug it out! ;-) Take care. Robb W ==================================== CDR Robert B. Wolov, MC, (FS), USNR Department of Orthopedic Pathology Armed Forces Institute of Pathology Washington, DC 20306-6000 wolov@hi*.co* (preferred) wolov@em*.af*.os*.mi*
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